High pressure metal vapor lamp



Feb. 17, 1942. H. c. RENTscHLER- HGH kPRESSURE METAL VAPOR LAMP FiledMarch 9, 1934 INVENTOR C. Flr/V ATTORN EY Patented Feb. .17, 1942 HIGHPRESSURE METAL VAPOR LAMP Harvey Clayton ltentscliler, East Orange, N.J., assignor to Westinghouse Lamp Company, a corporation of PennsylvaniaApplication Maren 9.1934, semi No. 114,162

9 claims. (c1. 11e-122) This invention relates to illuminating devicesand more particularly to devices of this character generally termed highpressure vapor arc lamps. In its more speciilc aspect the invention isparticularly directed to high pressure mercuryV arc lamps although it isnot speciiically limited thereto.

Heretofore high pressure mercury lamps have been proposed as anilluminating means. Lamps of this type have generally consisted of anenvelope in which is located a cathode and an anode. The anode is solid'and the cathode is a pool of mercury. Because of the mercury poolcathode, this type of lamp was subject to at least two majordisadvantages. First, the lamp could be operated only in those positionswhere the mercury pool remained in its proper position and, second,means had to be provided 'for regulating the thermal condition of themercury during operation of said lamp. When lamps of this character areoperated, it sometimes happens that the lamps suddenly extinguish andwill not restart until after a considerable period of time.

The high pressure mercury lamp is essentially an arc lamp inwhich arelatively high vapor pressure of the mercury is ymaintained duringoperation by the heat developed by the arc. The vapor pressure of themercury in said lamp duringI operation may be hundreds of millimeters ofmercury and as highas oneatmosphere. When will follow the gas law'thatit is directly proportional to the absolute temperature of the mercury.Thus the pressure of the mercury vapor can be only slightly affected byany changes in temperature thereof due to external conditions.

An object of my invention is to provide a simplined metal vapor arc lampwhich will operate over a very long period of time without extinguishingand without the employment of temperature regulating means.

Another object of my invention is to provide a simplified metal vaporarc lamp which may be operated in any desired position.

A still further object of my invention is to provide a metal vapor arclamp that is relatively cheap and has a high luminous eiiiciencyappreaching 50 L/W.

These and other objects of my invention will be apparent from thefollowing description and drawing wherein,

Figure l` is a view partly in section and partly in elevation of myimproved lamp.

Fig. 2 is an enlarged view of an electrode on the line II-II of Fig. 1in the direction of the arrows.

Fig. 3 is a cross sectional View on line III-III of Fig. 1 in thedirection of the arrows.

As shown in Figure l, my lamp comprisesa tubular vitreous envelope I0composed of a glass there is liquid mercury in the lamp duringoperation, as there always is in the prior art arc lamps, the Vaporpressure of -the mercury rises exponentially with thev rises intemperature of the mercury pool. If for some reason the temperature ofthe pool .is higher than that which it should be according to the lampdesign, the mercury pressure rises so high that the lamp willextinguish. I

In ordernto obviate this diiiiculty of controlling the temperature ofthe mercury pool during lamp operation, I have by my invention entirelyVeliminated this particular consideration. According to my invention, myhigh pressure mercury arc lamp operates without the presence of amercury pool. The amount of mercury in my lamp is so limited that all ofthe mercury contained in the lamp is entirely inthe vapor stateduringsteady lamp operation. Since the mercuryv is all in the vaporstate during steady lamp operation when a constricted luminous columnarc lies well within the walls` of the tube, any change in temperatureof the mercury vapor due to external conditions will only slightlyaffect the pressure of the mercury because ysaid pressure adapted towithstand the high temperature de-` veloped in said lamp duringoperation. If d'esired, the envelope may be composed of quartz.Leading-in conductors I I are sealed in small outwardly extendingpinches I2 in the opposite ends of the envelope and extend inwardly andoutwardly thereof. Each of vsaid conductors is electrically connected toand supports an electrode I3 of the cold-ho type. Each of saidelectrodes consists of a stick I4 or rod of a compound adapted toactivate-a tungsten wire I5 wound therearound, and a semi-circular heavytungsten rod I6 welded to the outer/ends of the tungsten The stick Ilmay be composed of a material which will not disintegrate and pulverizeduring positive ion bombardment thereof. Forv this purpose I employBaCOa-I-powdered tungsten mixed and sintered. According to my inventionthe electrodes I3 are located rather close to the ends of the envelopeI0 so that the temperature of that portion of the envelope behind theelectrodes is not so low that mercury will condense thereon and alsosothat aA uniform temperature distribution may be maintained throughoutthe envelope.

The envelope contains therein a charge of starting gas, such as argon,and a limited small proportion of mercury. 'I'he pressure of the argonmay be about 5 mm. of mercury. The envelope may be about inches long andabout one inch in diameter. The amount of mercury within said envelopemay be about 300 to 400 milligrams. With this small quantity of mercurywithin the envelope of my mercury arc lamp, it is all completelyvaporized during steady operation and the pressure and temperaturecharacteristics thereof follow the gas laws so that small changes intemperature thereof do not greatly affect the pressure thereof. Uponsteady operation, the luminous column is not a diffused glow, but is inthe form of a concentrated luminous rod spaced Well away from theinterior wall of the envelope.

In order to further increase the eilciency of my lamp and so that it mayefficiently operate with a vapor pressure of hundreds of millimeters ofmercury, I surround the same by an evacuated container 20, which alsosupports the lamp per se. The container has a reentrant stem 2| in whichare sealed supporting conductors 22, 23, 24 and 25, with conductors 22and 23 extending interiorly and exteriorly of said envelope andconductors 24 and 25 extending only into said envelope and terminatingin said press. Spaced around the lower end of said bulb l0 are threeother pinches 26 in which are sealed supporting rods 21 having theirlower ends Welded to the conductors 23, 24 and 25. The conductor Il iswelded to the conductor 22. A rod 28 of nickel or tungsten has one endwelded to the upper leading-in conductor Il and to the conductor 23.Conductors 30 and 3| are respectively welded to the upper and lowerlead-ins l I and extend along the envelope, but do not come in contactwith each other, there being a small space between their ends in orderthat the discharge maybe started within the envelope.

With my lamp I have found that the same may be readily started and aftera few minutes arcing of high luminosity will take place. 'Ihe operationis then steady and the lamp will not extinguish because the entiremercury charge is in a vaporous condition at this stage.

A lamp of this character is operated by placing the same between theterminals of the secondary of an appropriate transformer so that thedesired current at the requisite potential may be derived therefrom inorder that the lamp may operate with a highly luminous and eflicientarc.

'I'he term cold-hot electrodes as employed herein means electrodes whichare not heated normally by means of electrical energy applied from asource external to the lamp but which are cold when the lamp is rststarted and become heated to an elevated temperature by the ionicbombardment thereof shortly after the,

lamp is operated.

Although I have shown and described my invention I do not desire to bespecifically limited thereto as various other modifications of the samemay be made Without departing from the spirit and scope of the appendedclaims.

What is claimed:

l. A lamp comprising a hermetically sealed container, having a press, aplurality of leadingin conductors sealed in said press and extendingexteriorly and interiorly thereof, a plurality of supports also sealedin said press, an envelope located in said container, a plurality ofcold-hot electrodes in said envelope, said conductors being electricallyconnected to said electrodes, a plurality of rods sealed in saidenvelope, said rods cooperating with said supports to maintain saidenvelope in proper position.

2. An electrical discharge device comprising sealed inner and outerenvelopes, said outer envelope having a supporting press, an ionizablemedium and a pair of electrodes in said inner envelope, means forcausing a flow of electrical energy through said inner envelopeproducing a discharge between said electrodes, said means includinglead-in conductors extending from said press, one of said conductorsbeing continued from said press between the walls of said inner andouter envelopes, the full length of said inner envelope, so as toconnect with the electrode remote from said press, the other conductorconnecting directly with the near electrode, and means for supportingsaid inner envelope from said press, comprising a plurality of supportwires embedded in said press, supporting wires embedded in said innerenvelope, the outer ends of said supporting wires being secured to saidpressembedded wires and the lead-in conductor to the remote electrode.

3. An electrical discharge device comprising sealed inner and outerenvelopes, a pair of electrodes in said inner envelope, said innerenvelope also containing a filling of discharge-conducting gas and avaporizable metal in sufficiently small quantity that it can becompletely vaporized in the operation of the device, means to supplysufficient electrical energy to said device to completely vaporize saidvaporizable metal, said outer envelope having a press extending towardsaid inner envelope, and means extending from said press to the adjacentend portion of said inner envelope and supporting the latter therefrom.

4. An electrical discharge device comprising a sealed container having apress, a plurality of leading-in conductors sealed in said press andextending exteriorly and interiorly thereof, a plurality of supportsalso sealed in said press, an envelope enclosed in said container, aplurality of electrodes in said envelope, one disposed adjacent saidpress and one remote therefrom, said envelope also containing a fillingof conducting gas and a vaporizable metal in sufliciently small quantitythat it can be completely vaporized during operation of the device, saidconductors extending one to each electrode, and means sealed to thepress-adjacent end of said envelope and respectively united to saidpress-sealed supports and conductor which connects with the electroderemote from said press.

5. An electrical discharge device comprising an envelope having anelectrode disposed in each end thereof, each electrode comprising a rodof electron-emission material, a coil of tungsten wire surrounding saidrod, and a heavy curved tungsten rod the ends of which are secured tosaid coil, lead-in conductors extending through said envelope andconnected to said tungsten rods, a filling of discharge-conducting gasin said envelope, and a vaporizable metal also in said envelope and insuflciently small quantity that it can be completely vaporized in theoperation of the device, and means to supply sufficient electricalenergy t0 said lead-in conductors to completely vaporize said metal.

6. An electrical discharge device comprising an inner cylindricalenvelope with substantially semi-spherical ends provided with adischargeconductive filling including a metal vapor and operating with ahigh pressure discharge, activated electrodes disposedone in each endportion of said envelope and each comprising a rod of electron-emittingmaterial surrounded by a coil of refractory metal, an outer enclosingenvelope having a press, and supports extending from said press to theadjacent end portion of said inner envelope ,for maintaining the desiredrelationship therebetween. i

7. An electrical discharge lamp comprising a light-transmitting envelopeof high melting point vitreous material, a plurality of electrodesdisposed therein and each consisting of a rod of electron-emittingmaterial surrounded by a tungsten coil, a lling of inert gas in saidenvelope at a pressure of less than one atmosphere, and such al quantityof mercury in said envelope that at the operating temperature of thelamp said mercury is completely vaporized and the combined pressure ofthe gas and vapor exceeds one atmosphere.

8. An electrode for a discharge device comprising a rod of conductiveelectron-emission material, av refractory metal wire wound therearound,and a curved refractory metal rod with its ends welded to the outer endsof said wire for connecting said coil with a leading-in conductor.

9. An electrode for a discharge device comprising a sintered rod of amixture of barium carbonate and/ powdered tungsten, a tungsten WireWound therearound, and a. semi-circular heavy tungsten rod with its endswelded to the outer ends of said tungsten wire for connecting said coilwith a leading-in conductor.

HARVEY CLAYTON RENTSCHLER.

